Micromechanical structures, such as gears, pin joints, sliders, levers, and springs have been made and described previously in U.S. Pat. No. 4,740,410. Prior to this invention, however, no IC-processed micro motors have been fabricated that could be powered by electricity. With the development of such micro structures the importance of micro motors in the same size became apparent because of their many potential uses. Micro motors convert electric power into mechanical power and may be used to drive mechanical elements such as gears, cranks, and other mechanisms that have numerous applications in macroscopic assemblies.
An object of this invention is to provide both synchronous and asynchronous or stepper type micro motors having dimensions measured in the ranges afforded by present day microfabrication lithography, typically from tenths of micrometers to hundreds of micrometers.
Another object of the invention is to provide micro motors capable of converting electrical power into mechanical power to be positioned with high precision on a microscopic scale and to perform useful tasks.
A further object of this invention is to provide a method for making micro motors in a batch process using thin-film technology for the structural elements that incorporates steps for providing friction-reducing, wear-retarding, and reliability-improving characteristics. The method according to this invention makes possible the precise dimensional control of the micro motors despite their diminutive size.
Another object is to provide an improved method for making such micro motors by using thin-film materials such as Plasma-Enhanced-Chemical-Vapor-Deposited (PECVD) amorphous silicon thin films to protect metalization on the surface of the micro-motor chips from attach by etchants.
The invention has many potential applications in the micromechanical field which include providing mechanical power for miniature devices such as fans, centrifuges, movable mirrors, and geared mechanisms in addition to many other electromechanical system uses. The new micro motors of this invention can be batch-fabricated together with other mechanical or electromechanical devices and with electric circuits to form more complex and highly useful microminiature electromechanical systems.